The present disclosure relates generally to systems and methods for processing seismic data acquired by one or more seismic receivers to identify locations of hydrocarbon formations or deposits within subterranean regions of the earth. Seismic exploration involves surveying subterranean geological formations for hydrocarbon deposits. A survey typically involves deploying seismic source(s) and seismic receivers at predetermined locations at or near the surface of the Earth. The sources generate seismic waves, which propagate into the subterranean geological formations creating pressure changes and vibrations along the way. Changes in elastic properties of a geological formation scatter the seismic waves, changing the direction of propagation and other properties of the seismic waves. Part of the energy emitted by the sources is reflected back from the geological formations toward the surface and reaches the seismic receivers. Some seismic receivers are sensitive to pressure changes (e.g. hydrophones), others to particle motion (e.g. geophones), and surveys may deploy only one type of receiver or both.
In response to the detected seismic events, the receivers generate electrical signals to produce seismic data. Analysis of the seismic data can be processed to indicate the presence or absence of probable locations of hydrocarbon deposits. Additionally, seismic sources and receivers may be used to monitor hydrocarbon production from a subterranean reservoir and/or other fluid flow within the reservoir.
Some surveys are known as “marine” surveys because they are conducted in marine environments, which may include saltwater environments, fresh water environments, and brackish water environments. In one type of marine survey, called a “towed-array” survey, an array of seismic receiver-containing streamers is towed behind a survey vessel which also tows one or more seismic sources. A possible alternative, or addition, to the use of towed streamers is the use of ocean bottom cables or ocean bottom nodes which contain seismic receivers. Unlike streamers, these lay on the sea bed and do not move during recording of seismic data. In such a survey the seismic sources may be towed by a vessel. There are also survey procedures in which the seismic sources are stationary (e.g. attached to a moored buoy).
Regardless of whether the receivers and seismic source(s) are moving or stationary, the received data can incorporate effects resulting from the methodology used to generate the seismic waves which penetrate into the subterranean and/or undersea geological formation. These source-side acquisition effects include signatures of the seismic sources, radiation patterns, residual shot noise, data irregularity, sparse data sampling, effects from the use of more than one seismic source, effects from motion of the seismic source (e.g., if it is moving while data is being acquired), the effect of the water surface above the seismic source(s), and the like. As such, the seismic data collected at the receivers (i.e. the seismic measurements made by the receivers) may be processed to remove or reduce artifacts which do not correspond to features of the geological formations that are being surveyed.